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991.
In recent years, demands for car transportation by a ship have been increasing with favorable economic conditions in auto
sector, and the need of a pure car carrier (PCC) has grown quickly. A PCC needs huge parking space but smaller displacement
since a car is comparatively light for its volume. As a result, almost all PCCs have wide breadth, shallow draft and huge
structure above the water surface. These features cause some technical issues of a PCC, like lack of stability, effect of
strong winds on its resistance, difficulty of course keeping in rough seas, difficulty of berthing in strong winds, and so
on. To overcome these technical issues, one of the authors has proposed a new concept for a PCC. This is a trimaran PCC which
has very limited transverse bulkheads in the center hull by using two side hulls as fenders. In the present research, wind
forces acting on a scale model of the trimaran PCC were measured in the towing tank with a wind generator at Osaka Prefecture
University. Furthermore, in order to clarify the characteristics of wind pressure on the trimaran, height and width of tunnels
which are between a main hull and side hulls were changed. And then, in order to imitate a real ship, we used wind reduction
technology of corner-cut design for accommodation house of the ship. Moreover, the wind pressure acting on the trimaran was
compared with that on a mono-hull PCC. Using these experimental and theoretical results, an estimation method of wind pressure
acting on the trimaran PCC is deduced. 相似文献
992.
To provide a suitable model for AUV simulation and control purposes, a general nonlinear dynamic model including a novel thruster
hydrodynamics model was derived. Based on the modeling method, the “AUV-XX” simulation platform was established to carry out
fundamental tests on its motion characteristics, stability, and controllability. A motion control strategy consisting of both
position and speed control in a horizontal plane was designed for different task assignments of underwater vehicles. Combined
control of heave and pitch was adopted to compensate for the reduction of vertical tunnel thrusters when the vehicle is moving
at a high speed. An improved S-surface controller based on the capacitor plate model was developed with flexible gain selections
made possible by different forms of restricting the error and changing the rate of the error. Simulation results show that
the derived general mathematical model together with simulation platform can provide a test bed for fundamental tests of motion
control. Additionally, the capacitor plate model S-surface control shows a good performance in guiding the vehicle to achieve
the desired position and speed with sufficient accuracy. 相似文献
993.
A terminal sliding mode fuzzy control based on multiple sliding surfaces was proposed for ship course tracking steering, which
takes account of rudder characteristics and parameter uncertainty. In order to solve the problem, the controller was designed
by employing the universal approximation property of fuzzy logic system, the advantage of Nussbaum function, and using multiple
sliding mode control algorithm based on the recursive technique. In the last step of designing, a nonsingular terminal sliding
mode was utilized to drive the last state of the system to converge in a finite period of time, and high-order sliding mode
control law was designed to eliminate the chattering and make the system robust. The simulation results showed that the controller
designed here could track a desired course fast and accurately. It also exhibited strong robustness peculiarly to system,
and had better adaptive ability than traditional PID control algorithms. 相似文献
994.
Mathematical models of propellers were created that investigate the influence of periodic boundary conditions on predictions
of a propeller’s performance. Thrust and torque coefficients corresponding to different advance coefficients of DTMB 4119,
4382, and 4384 propellers were calculated. The pressure coefficient distribution of the DTMB 4119 propeller at different sections
was also physically tested. Comparisons indicated good agreement between the results of experiments and the simulation. It
showed that the periodic boundary condition can be used to rationally predict the open water performance of a propeller. By
analyzing the three established modes for the computation, it was shown that using the spline curve method to divide the grids
can meet the calculation’s demands for precision better than using the rake cutting method. 相似文献
995.
The seakeeping performance of a luxury cruise ship was evaluated during the concept design phase. By comparing numerical predictions
based on 3-D linear potential flow theory in the frequency domain with the results of model tests, it was shown that the 3-D
method predicted the seakeeping performance of the luxury cruise ship well. Based on the model, the seakeeping features of
the luxury cruise ship were analyzed, and then the influence was seen of changes to the primary design parameters (center
of gravity, inertial radius, etc.). Based on the results, suggestions were proposed to improve the choice of parameters for luxury cruise ships during the
concept design phase. They should improve seakeeping performance. 相似文献
996.
人字齿轮减振降噪的修形设计(英文) 总被引:1,自引:0,他引:1
To reduce vibration and noise and increase transmission efficiency, a three segment method for modifying the pinion profile
was proposed. Cutter surface equations were deduced by changing the shape of the cutter-edge, substituting three segment parabolas
for the line. The influence of longitudinal tooth modifications on tooth surface load distributions was discussed. Transmission
error minimization and uniformity of tooth surface load distribution were chosen as optimization goals and the modified parameters
were obtained by applying the complex method. Finally, an experiment comparing the loaded transmission error, vibration, and
noise both before and after modifications was carried out. The results indicate that the modified design is reliable. 相似文献
997.
The effect of line voltage drop is considered larger on loads, especially on asynchronous motor, transformers and other non-linear
load parameters in power system of large ships. A novel power flow method based on improved node voltage method is proposed,
and a typical ship power system, which has 2 power stations and 10 nodes, with closed-loop design but open-loop operation,
is taken as an example. Simulation results show that the improved power flow calculation method has achieved higher accuracy
and better convergence. 相似文献
998.
Problems experienced during Floating Production, Storage and Offloading (FPSO) tandem offloading operations were investigated.
The aim of this research was to improve the reliability of such systems, and it needed a means to assess them. Time-domain
simulation and analysis of offloading systems was performed using the multi-body mooring software ARIANE 7.0. Hydrodynamic
interaction between the vessels was considered. The responses of the offloading system in different loading cases, different
parameters of offloading hawsers and the effects of challenging environmental conditions were calculated. There was a focus
on the problems of relative motion between the two bodies and its effects on the intensity of hawser forces. Minimum relative
distance, maximum relative headings and maximum tension in the hawsers of offloading systems were obtained by time-domain
analysis. The time-domain analysis was effective and comparative study can be used to optimize parameters of the system and
extend operating limits. 相似文献
999.
海上风力机安装技术研究(英文) 总被引:1,自引:0,他引:1
Wind power has made rapid progress and should gain significance as an energy resource, given growing interest in renewable
energy and clean energy. Offshore wind energy resources have attracted significant attention, as, compared with land-based
wind energy resources, offshore wind energy resources are more promising candidates for development. Sea winds are generally
stronger and more reliable and with improvements in technology, the sea has become a hot spot for new designs and installation
methods for wind turbines. In the present paper, based on experience building offshore wind farms, recommended foundation
styles have been examined. Furthermore, wave effects have been investigated. The split installation and overall installation
have been illustrated. Methods appropriate when installing a small number of turbines as well as those useful when installing
large numbers of turbines were analyzed. This investigation of installation methods for wind turbines should provide practical
technical guidance for their installation. 相似文献
1000.
CHENMing-jie LIDian-pu ZHANGAi-jun 《船舶与海洋工程学报》2004,3(1):64-70
Chaotic synchronization is a branch of chaotic control. Nowadays, the research and application of chaotic synchronization have become a hot topic and one of the development directions is for the research on chaos. In this paper, a universal nonlinear stateobserver is presented for a class of universal chaotic systems to realize the chaotic synchronization, according to the theory of state-observer in the modem control theory. And theoretic analysis and simulation results have illustrated the validity of the approach. Moreover, the approach of synchronization proposed in this paper is very easy, flexible and universal with high synchronization precision. When the approach is applied to secure communication, the results are satisfying. 相似文献